Program for checking balance of parenthesis in C using stack but it is not working as expected plz help me with it. Thanks

        #include<stdio.h>
		#include<stdlib.h>
		#include<string.h>
		struct node{
			char data;
			struct node *next;
		};
		struct node *top=NULL;   //top stores address of top element of stack
		void push(char data)     //inserting element
		{
		struct node *temp = (node *)malloc(sizeof(struct node));
			temp->data=data;
			temp->next=NULL;
			if(top==NULL)
			{
				top=temp;
				return;
			}
			temp->next=top;
			top=temp;
		}
		void pop()  //removing element
		{
			struct node *temp=top;
			if(top==NULL)
			{
				printf("No element to delete");
				return;
			}
			top=top->next;
			free(temp);
			}
		char Top()  //fn tht return top element of stack
		{
	       return top->data;
		}
		int isEmpty()
		{
			if( top!=NULL)
			{
		       return 1;
			}
			else
			return 0;
		}
		int ArePair(char opening,char closing)
		{
			if(opening == '(' && closing == ')')
			return 1;
			else if(opening == '{' && closing == '}')
			 return 1;
			else if(opening == '[' && closing == ']')
			return 1;
			return 0;
		}
		int Arebalanced(char exp[])
		{
			int i;
			for(i=0;i<strlen(exp);i++)
			{
				if(exp[i] == '(' || exp[i] == '{' || exp[i] == '[')
					push(exp[i]);
				else if(exp[i] == ')' || exp[i] == '}' || exp[i] == ']')
				{
					if(isEmpty() || !ArePair(Top(),exp[i]))
						return 0;
					else
			           pop();
				}
			}
			return isEmpty() ? 1:0;
		}
		int main()
		{
		    int i;
		    char a[50];
			printf("Enter expession: ");
			gets(a);
			if(Arebalanced(a))
			{
				printf("balanced \n");
			}
			else
			printf("not balanced\n");
		}